In calculating the quantity required for a roof, you need to know the roof type, ratio of roof length to roof width, roof slope, shingle exposure, type of cedar shingle used (more breakage with lower grades), type of hip and ridge units (prefabricated or built on site) and general surface area.

WALLS

For cedar siding, calculate the total area and divide by the area covered by a square. As walls are less exposed to climate, a greater exposure can be used, and less shingles are required. ﻿

Here is a calculator that will help you find out how many bundles you need for your job. The greater the exposure, the less shingles you require.﻿